Take-up for sewing machines.



R. K. HOHMANN.

TAKE-UP FOR SEWING MACHINES.

APPLICATION FILED DEC. 3, 1910.

1,073,489. Patented Sept. 16,1913.

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RICHARD K. HOHMANN, OF SAN DIEGO, CALIFORNIA.

TAKE-UP FOR SEWING-MACHINES.

Application filed December 3, 1910.

To all whom it may concern Be it known that I, RICHARD K. 1101!- MANN, acitizen of the United States, and resident of San Diego, county of SanDiego, State of California have invented certain new and usefulImprovements in Take-Ups for SewingMachines, of which the following is aspecification.

This invention relates to the take-up for sewing machines. and has beenparticularly designed for use in a rotary sewing machine in which thelower thread holder carries an ordinary spool of thread.

It has been my object to so time the parts and to so regulate the speedof motion of the take-up in the cycle of its movements as to moreaccurately and etliciently form the loop to be engaged by the lowerthread looping means and to supply the proper length of thread at theright time in order to pass freely around the bobbin.

The novel features of the invention will be apparent from the followingdescription taken in connection with the accompanying drawings.

In the drawings, Figure 1 is a face view of the head of the machinehaving the face plate removed and showing my invention applied thereto;Fig. 2 is a detail front view of the take-up mechanism removed.

In the drawings 1 represents the ordinary head of a sewing machine inwhich is mounted the vertically reciprocating needle bar 2 and also thepresser foot bar These parts are of the usual construction and need notbe described in detail.

In the frame of the machine and extending into the head there is arotary shaft which has Within the head two separate crank arms whichcarry the crank pins .1 and 5. In the particular form shown the crankarms are in the shape of circular disks, one behind the other in Fig. 1,but it will be understood that the particular form of these arms is nopart of my present invention. The crank pin .1 has pivotally securedthereto a link 6 which is pivotally secured at its other end to theneedle bar 2, so that the rotation of the shaft and crank serves toreciprocate the needle bar in order to form the stitch. The crank pin 5is on the face of the crank arm or disk 7 and it preferably carries aroller for the purpose of reducing friction and this is the roller whichoperates the take-up mechanism of the machine. One arrangement of mecha-Specification of Letters Patent.

ltatcntcd Slept. 11.45, 1913..

Serial No. 595,529.

nism by which the crank arms are supported is illustrated in my prior.latent No. 9111130, but it will he understood that the invention is notcontincd to that pa rticular form.

The take up in the particular form shown embodies a take-up shaft 8 andan arm 9 which extends out to the side of the head of the machine andcarries at its outer end an eye 10 to receive the thread. Another arm1.1 extends from the take-up shaft and is provided with an irregularlyshaped slot in which the pin 5 works and it will be seen by reference toFig. 1 that the shaft of the take-up device is mounted just beyond theedge of the circular path in which the pin 5 moves so that at one pointof its revolution the pin 5 approaches the pivot of the takeup veryclosely and this occurs during the upward movement of the pin The resultof this is that the take-up is quickly raised and the structure is suchthat practically all of the upward movement occurs during onelourth ofthe revolution of the pin The slot in the arm 11 is prmztically straightfrom its inner end next to the shaft 8 out to the point .12 near thecenter where it takes an upward bend thus forming what may he termed ahump from the point 12 to the point 13. From the point 13 to the outerend the slot has a uniform downward curve. The purpose of the upwardbend or hump is to give to the take-up a slight movement downward at atime just before such downward movement would commence if a straightslot were used and by means of this upward bend the downward motion ofthe take-up is accelerated at the beginning so as to supply thenecessary thread for use in forming the loop to be engazjcd by therotary mechanism below the table. it will be observed that when this arm11. is in its lowest position, the upward bend will have the reverseeffect and will tend to give to the take up a dwell in its lowestposition. ln other words the bend will tend to give to the take-up adownward impulse when the arm 11 starts on its upward movement so thatthe resultant etl'ect of the bend and the upward movement of the armwill be practically a dwell. it will 't'turthcr be observed from Fig. 1that the downward motion of the take-up is accelerated by the hump whenthe needle bar has moved about half way down and. is just entering thecloth. The loop which is to be engaged by the ro tary hook beneath thecloth must be formed after the needle goes through the cloth andcommences its upward movement and Ihave found by experiment that anaccelerated supply of thread when the needle enters the cloth greatlyimproves the results and prevents the skipping of stitches and thebreaking of the thread. It permits a more per feet formation of the loopto be engaged by the hook. In Fig. 1 the relative positions of thetake-up arm and the link 6 are shown in dotted lines, the full lineposition of link 6 being omitted to avoid confusion in the illustration.The pins t and 5 are about 170 apart in the circle of their movement andthe result is that the pin 5 reaches the upward bend in the take-upbefore the needle bar reaches the lower limit of its movement and thusthe takeup is given its initial downward movement so as to supply anexcess of the thread just at the time when it is needed. I have foundthat this form of take-up is very efiicient when used in connection withthe large bobbin holder for the lower thread constructed to receive anordinary spool of thread since in that case the loop must be large andsuflicient thread must be supplied at the proper time to form it.

It will be understood that the particular form of the take-up mechanismis not essential to my invention in its broad aspect, so

long as there is the rotary pin and the 00-- In a sewing machine, thecombination with a rotary crank having a crank pin, of a take-up rockshaft mounted in bearings just beyond the circular path of said pin andapproximately on a level with the lower limit of the movement of saidpin, and an arm extending from said rock shaft having therein aslotin'which said pinworks, the said slot being straight in that portionnext to the shaft having an upward curve or hump near its center and adownward uniform curve from the center to the outer end.

In testimony whereof I affix my signature in presence of two witnesses.

RICHARD K. noHMANN;

Witnesses Lon Hosxmson, ARTHUR L. BRYANT.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, I). G.

